The correct sequence should be as follows:
1. Pausch explains the reason for his last lecture.
2. Pausch outlines what the lecture will cover.
3. Pausch shares his childhood aspirations and how he realized them.
4. Pausch discusses how he assisted others in achieving their dreams.
During his "Last Lecture," which was actually titled Really Achieving Your Childhood Dreams, computer science professor Randy Pausch elaborated on why this would be his final lecture, followed by detailing that the lecture would focus on dreams and their attainment. He then shared his childhood dreams and how he turned them into reality. The second part of the lecture shifted to helping others reach their potential and fulfill their own aspirations. He passed away from pancreatic cancer on July 25th, 2008, at the age of 47.